Modern agriculture strongly relies on mineral fertilizers that make it possible to increase the arable land productivity fast and cost-effective. The traditional use of fixed doses of mineral fertilizers under a free market economy is ineffective, as it does not reflect the character of soil fertility. The article explores the causes of hereditary links between nutrient removal and harvest elements. To plan the activities of agricultural enterprises it is required to use mathematical models for calculating the doses of mineral fertilizers. As initial data, the authors used the results of long-term experiments conducted at the Department of Soil Science and Agrochemistry of the Northern Trans-Ural State Agricultural University. The scheme of the experiment included the application of mineral fertilizers to the planned yield in spring wheat 3.0; 4.0; 5.0 and 6.0 t/ha. Mineral fertilizers were applied taking into account soil fertility that was estimated annually. In experiments, the content of nutrients in straw and grain was determined annually; removals were calculated. The data obtained shaped the basis for the development of a mathematical model for spring wheat feeding. There was revealed: a high correlation between nutrients and biogenic removal; the ratio of grain to straw; yield of the byproducts at harvest. Regression equations can be used to calculate the doses of mineral fertilizers for the planned yield in grain crops. A high approximation coefficient confirms the reliability of the derived equations. A regression mathematical model of correlated indicators is presented. The indicators can be used to optimize the fertilizer system, to plan agricultural enterprises and in studies as well.